The present invention relates to coating compositions comprising an organic film-forming binder, preferably a coating material, and certain aminophosphonic acids or aminophosphorous acids and/or their zirconium, bismuth and calcium salts, and salts thereof with certain amines, as corrosion inhibitors, to the use thereof in coating compositions for protecting metallic surfaces, and to novel aminophosphonic acids and novel salts of aminophosphonic acids and of aminophosphorous acids.
The use of alkali metal, alkaline earth metal, transition metal and amine salts of carboxylic acids, and of transition metal complexes of ketocarboxylic acids, as corrosion inhibitors in aqueous systems is known and is described, for example, in U.S. Pat. No. 4,909,987, EP-A-0 412 933, EP-A-0 496 555, EP-A-0 554 023 or EP-A-0 619 290.
EP-A-0 437 722 discloses certain amine oxides of phosphonic acids as corrosion inhibitors. U.S. Pat. No. 4,000,012 describes an anticorrosion effect of iron phosphate or zinc phosphate coatings on steel, the action of which is markedly improved by treatment with a solution of an xcex1-aminophosphonic acid or water-soluble salts thereof. U.S. Pat. No. 4,076,501 refers to an anticorrosion effect of metals by means of diphosphonic acids. U.S. Pat. No. 4,917,737 describes a method of sealing off a phosphated metal substrate using certain alkylaminodiphosphonic acids. U.S. Pat. No. 3,925,245 (DE-A-2 231 206) refers to a corrosion-inhibiting composition for metal surfaces, comprising inorganic nitrites and aminoalkylphosphonic acids. U.S. Pat. No. 3,837,803 (DE-A-2 335 331) relates to a process of corrosion inhibition for metallic components which are in contact with aqueous systems, through the use of synergistic mixtures of water-soluble organophosphonic acids and their salts, a water-soluble orthophosphate, and calcium ions. U.S. Pat. No. 3,483,133 relates to the use of certain aminomethylphosphonic acids as corrosion inhibitors for metals in aqueous systems. GB-A-1 201 334 likewise discloses the use of certain phosphonic acids as corrosion inhibitors for metals in aqueous systems.
GB-A-2 121 419 discloses the use of certain phosphonic acids as corrosion inhibitors in coating materials.
One of the objects of the invention, then, was to providexe2x80x94specifically for coating systems, especially those which are water-basedxe2x80x94a coating composition which, firstly, inhibits or eliminates entirely the corrosion of metals, and, secondly, promotes good adhesion of the coating to the metal.
It has been found that certain aminophosphonic acids or aminophosphorous acids and/or their zirconium, bismuth and calcium salts, and also the salts thereof with certain amines, surprisingly suppress the oxidation of metals, and at the same time they greatly improve the adhesion of the coating to the metal. These acids and salts are for the most part novel, and are particularly suitable in the novel coating compositions both as corrosion inhibitors and as adhesion promoters.
The invention therefore relates to coating compositions comprising
a) an organic film-forming binder, and
b) as corrosion inhibitor xcex1) at least one compound of the formula I 
xe2x80x83in which
R1 is hydroxyl-, carboxyl- or amino-substituted C4-C12alkyl; or R1 and R5, together with the nitrogen atom to which they are attached, form a 5-, 6- or 7-membered heterocyclic ring which is unsubstituted or is substituted by C1-C4alkyl or is interrupted by oxygen, sulfur or 
R2 and R3 independently of one another are hydrogen, C1-C20alkyl, C5-C8cycloalkyl, unsubstituted or C1-C4alkyl-substituted phenyl; or are benzyl,
R4 is hydroxyl,
R5 is 
R6 is C1-C18alkyl or C7-C9phenylalkyl, and
m is 0 or 1; or
xcex2) at least one salt derived from i) a compound of the formula Ixe2x80x2
xe2x80x83in which
Rxe2x80x21 is hydrogen, C1-C25alkyl, C3-C25alkyl interrupted by oxygen, sulfur or 
xe2x80x83hydroxyl-, carboxyl- or amino-substituted C2-C25alkyl; C2-C24alkenyl, C4-C15cycloalkyl, unsubstituted or C1-C4alkyl-substituted phenyl; C7-C9phenylalkyl or 
xe2x80x83or Rxe2x80x21 and Rxe2x80x25, together with the nitrogen atom to which they are attached, form a 5-, 6- or 7-membered heterocyclic ring which is unsubstituted or is substituted by C1-C4alkyl or is interrupted by oxygen, sulfur or 
Rxe2x80x24 is hydrogen, hydroxyl or xe2x80x94OR8,
Rxe2x80x25 is hydrogen, C1-C25alkyl, C3-C25alkyl interrupted by oxygen, sulfur or 
xe2x80x83C2-C24alkenyl, C4-C15cycloalkyl, unsubstituted or C1-C4alkyl-substituted phenyl; C7-C9-phenylalkyl or 
R7 is hydrogen or C1-C6alkyl,
R8 is C1-C6alkyl, C4-C15cycloalkyl or unsubstituted or C1-C4alkyl-substituted phenyl; with the proviso that, if Rxe2x80x21 or Rxe2x80x25 is hydrogen, m is 0; and
ii) an amine of the formula II 
xe2x80x83in which
R14 and R15 independently of one another are hydrogen, C1-C25alkyl, hydroxyl-substituted C2-C24alkyl, C3-C25alkyl interrupted by oxygen or sulfur; C7-C9-phenylalkyl which is unsubstituted or is substituted on the phenyl ring by C1-C4alkyl; C3-C24alkenyl or 
xe2x80x83or R14 and R15, together with the nitrogen atom to which they are attached, form a 5-, 6- or 7-membered heterocyclic ring which is unsubstituted or is substituted by C1-C4alkyl or is interrupted by oxygen, sulfur or 
R16 is C1-C25alkyl, C2-C25alkyl which is interrupted by oxygen or sulfur; hydroxyl, C1-C18alkoxy or C2-C24alkenyl,
R17 is hydroxyl, C1-C18alkoxy, or C2-C18alkoxy which is interrupted by oxygen or sulfur; and, if b is 0, three radicals R17 together are N(CH2CH2Oxe2x80x94)3,
X is a direct bond, C1-C18alkylene, C2-C20alkylidene, C7-C20 phenylalkylidene, C5-C8cycloalkylene, unsubstituted or C1-C4alkyl substituted phenylene or naphthylene;
or is C4-C18alkylene which is interrupted by oxygen, sulfur or 
xe2x80x83with the proviso that never two nitrogen atoms are attached to the same carbon atom,
a is 1 or 2,
b is 0, 1 or 2, and,
if a is 1,
R18 is hydrogen, C1-C25alkyl, hydroxyl-substituted C2-C24alkyl, C3-C25alkyl which is interrupted by oxygen or sulfur; unsubstituted or C1-C4alkyl-substituted phenyl; C7-C9-phenylalkyl which is unsubstituted or is substituted on the phenyl ring by C1-C4alkyl;
C3-C24alkenyl, 
xe2x80x83if a is 2,
R18 is 
xe2x80x83and with the proviso that, if in the compound of the formula Ixe2x80x2 Rxe2x80x21 is C1-C12alkyl, 
xe2x80x83or 2-hydroxyethyl, Rxe2x80x25 is 
xe2x80x83R2 and R3 are hydrogen, Rxe2x80x24 is hydroxyl and m is 0, and, if in the compound of the formula II a is 1 and X is a direct bond, then at least one of the radicals R14, R15 and R18 is other than hydrogen; or
iii) zirconium, bismuth or calcium.
Hydroxyl-, carboxyl- or amino-substituted C2-C2alkyl is a branched or unbranched radical which contains preferably 1 to 3, in particular 1 or 2, hydroxyl, carboxyl or amino groups, such as, for example, hydroxyethyl, carboxyethyl, aminoethyl, 3-hydroxypropyl, 3-carboxypropyl, 3-aminopropyl, 2-hydroxypropyl, 2-carboxypropyl, 2-aminopropyl, 4-hydroxybutyl, 4-carboxybutyl, 4-aminobutyl, 3-hydroxybutyl, 3-carboxybutyl, 3-aminobutyl, 2-hydroxybutyl, 2-carboxybutyl, 2-aminobutyl, 5-hydroxypentyl, 5-carboxypentyl, 5-aminopentyl, 4-hydroxypentyl, 4-carboxypentyl, 4-aminopentyl, 3-hydroxypentyl, 3-carboxypentyl, 3-aminopentyl, 2-hydroxypentyl, 2-carboxypentyl, 2-aminopentyl, 6-hydroxyhexyl, 6-carboxyhexyl, 6-aminohexyl, 5-hydroxyhexyl, 5-carboxyhexyl, 5-aminohexyl, 4-hydroxyhexyl, 4-carboxyhexyl, 4-aminohexyl, 3-hydroxyhexyl, 3-carboxyhexyl, 3-aminohexyl, 2-hydroxyhexyl, 2-carboxyhexyl, 2-aminohexyl, 7-hydroxyheptyl, 7-carboxyheptyl, 7-aminoheptyl, 6-hydroxyheptyl, 6-carboxyheptyl, 6-aminoheptyl, 5-hydroxyheptyl, 5-carboxyheptyl, 5-aminoheptyl, 4-hydroxyheptyl, 4-carboxyheptyl, 4-aminoheptyl, 3-hydroxyheptyl, 3-carboxyheptyl, 3-aminoheptyl, 2-hydroxyheptyl, 2-carboxyheptyl, 2-aminoheptyl, 8-hydroxyoctyl, 8-carboxyoctyl, 8-aminooctyl, 7-hydroxyoctyl, 7-carboxyoctyl, 7-aminooctyl, 6-hydroxyoctyl, 6-carboxyoctyl, 6-aminooctyl, 5-hydroxyoctyl, 5-carboxyoctyl, 5-aminooctyl, 4-hydroxyoctyl, 4-carboxyoctyl, 4-aminooctyl, 3-hydroxyoctyl, 3-carboxyoctyl, 3-aminooctyl, 2-hydroxyoctyl, 2-carboxyoctyl, 2-aminooctyl, 9-hydroxynonyl, 9-carboxynonyl, 9-aminononyl, 10-hydroxydecyl, 10-carboxydecyl, 10-aminodecyl, 11-hydroxyundecyl, 11-carboxyundecyl, 11-aminoundecyl, 12-hydroxydodecyl, 12-carboxydodecyl, 12-aminododecyl, 13-hydroxytridecyl, 13-carboxytridecyl, 13-aminotridecyl, 14-hydroxytetradecyl, 14-carboxytetradecyl, 14-aminotetradecyl, 15-hydroxypentadecyl, 15-carboxypentadecyl, 15-aminopentadecyl, 16-hydroxyhexadecyl, 16-carboxyhexadecyl, 16-aminohexadecyl, 17-hydroxyheptadecyl, 17-carboxyheptadecyl, 17-aminoheptadecyl, 18-hydroxyoctadecyl, 18-carboxyoctadecyl, 18-aminooctadecyl, 20-hydroxyeicosyl, 20-carboxyeicosyl, 20-aminoeicosyl, 22-hydroxydocosyl, 22-carboxyeicosyl or 22-aminoeicosyl. A preferred definition of R1 is hydroxyl-, carboxyl- or amino-substituted C4-C12alkyl, especially hydroxyl- or carboxyl-substituted C5-C12alkyl, for example hydroxyl- or carboxyl-substituted C5-C11alkyl. A particularly preferred definition of R1 is hydroxyl- or carboxyl-substituted C5-C10alkyl, especially hydroxyl- or carboxyl-substituted C5-C8alkyl, for example hydroxyl-substituted C5-C6alkyl. An especially preferred definition of R1 is 5-hydroxypentyl. A preferred definition of Rxe2x80x21 is hydroxyl-, carboxyl- or amino-substituted C2-C20alkyl, especially hydroxyl-, carboxyl- or amino-substituted C5-C20alkyl, for example hydroxyl-, carboxyl- or amino-substituted C5-C12alkyl. A particularly preferred definition of Rxe2x80x21 is hydroxyl- or carboxyl-substituted C5-C12alkyl, especially hydroxyl- or carboxyl-substituted C5-C11alkyl, for example 5-hydroxypentyl or 11-carboxyundecyl. A particularly preferred definition of Rxe2x80x31 is hydroxyl-, carboxyl- or amino-substituted C4-C14alkyl, especially hydroxyl- or carboxyl-substituted C5-C14alkyl, for example hydroxyl- or carboxyl-substituted C5-C11alkyl. One of the preferred definitions of R14, R15 and R18 (if a=1) is hydroxyl-substituted C2-C24alkyl, especially hydroxyl-substituted C2-C20alkyl, for example hydroxyl-substituted C2-C14alkyl. A particularly preferred definition of R14, R15 and R18 is hydroxyl-substituted C2-C12alkyl, especially hydroxyl-substituted C2-C8alkyl, for example hydroxyl-substituted C2-C4alkyl, such as 2-hydroxyethyl, for example.
Where R1 and R5 or Rxe2x80x21 and Rxe2x80x25 or Rxe2x80x31 and Rxe2x80x35 or R14 and R15, together with the nitrogen atom to which they are attached, form a 5-, 6- or 7-membered heterocyclic ring which is unsubstituted or is substituted by C1-C4alkyl or is interrupted by oxygen, sulfur or 
this denotes, for example, the following radicals: 
R14 and R15 preferably form, with the nitrogen atom to which they are attached, a 6-membered heterocyclic ring interrupted by oxygen, such as, for example, 
Alkyl having up to 25 carbon atoms is a branched or unbranched radical such as, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethyl-butyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl or docosyl. A preferred definition of R2 and R3 is C1-C20alkyl, especially C1-C12alkyl, for example C1-C8alkyl. A particularly preferred definition of R2 and R3 is C1-C6alkyl, especially C1-C4alkyl, for example methyl. A preferred definition of R6 is C1-C18-alkyl, especially C1-C12alkyl, for example C1-C8alkyl. A particularly preferred definition of R6 is C1-C6alkyl, especially C1-C4alkyl, for example methyl or ethyl. A preferred definition of Rxe2x80x21 and Rxe2x80x25 is C1-C25alkyl, especially C5-C20alkyl, for example C5-C18alkyl. A preferred definition of Rxe2x80x31 and Rxe2x80x35 is C8-C14alkyl. A preferred definition of R7 is C1-C6alkyl, especially C1-C4alkyl, for example methyl. A preferred definition of R8 is C1-C6alkyl, especially C1-C4alkyl, for example methyl or ethyl. A preferred definition of R14, R15, R16 and R18 is C1-C20alkyl, especially C1-C14alkyl, for example C1-C12alkyl. A particularly preferred definition of R14, R15, R16 and R18 is C1-C8alkyl, especially C1-C4alkyl, for example methyl or ethyl.
C4-C15cycloalkyl is, for example, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl, cyclotridecyl, cyclotetradecyl or cyclopentadecyl. A preferred definition of Rxe2x80x21, R2, R3, Rxe2x80x25 and R8 is C5-C8cycloalkyl, especially C6-C7cycloalkyl, for example cyclohexyl.
C1-C4alkyl substituted phenyl which preferably contains 1 to 3, in particular 1 or 2, alkyl groups, is, for example, o-, m- or p-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5dimethylphenyl, 2,6-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, 2-methyl-6-ethylphenyl, 4-tert-butylphenyl, 2-ethylphenyl or 2,6-diethylphenyl.
C7-C9phenylalkyl which is unsubstituted or is substituted on the phenyl radical by from 1 to 3 C1-C4alkyl is, for example, benzyl, xcex1-methylbenzyl, xcex1,xcex1-dimethylbenzyl, 2-phenylethyl, 2-methylbenzyl, 3-methylbenzyl, 4-methylbenzyl, 2,4-dimethylbenzyl, 2,6-dimethylbenzyl or 4-tert-butylbenzyl. Benzyl is preferred.
C3-C25alkyl which is interrupted by oxygen, sulfur or 
is, for example, CH3xe2x80x94Oxe2x80x94CH2CH2xe2x80x94, CH3xe2x80x94Sxe2x80x94CH2CH2xe2x80x94, CH3xe2x80x94NHCH2CH2xe2x80x94, CH3xe2x80x94N(CH3)CH2CH2xe2x80x94, CH3xe2x80x94Oxe2x80x94CH2CH2xe2x80x94Oxe2x80x94CH2CH2xe2x80x94, CH3xe2x80x94(Oxe2x80x94CH2CH2xe2x80x94)2Oxe2x80x94CH2CH2xe2x80x94, CH3xe2x80x94(Oxe2x80x94CH2CH2xe2x80x94)3Oxe2x80x94CH2CH2xe2x80x94 or CH3xe2x80x94(Oxe2x80x94CH2CH2xe2x80x94)4Oxe2x80x94CH2xe2x80x94.
Alkenyl having 2 to 24 carbon atoms is a branched or unbranched radical such as, for example, vinyl, propenyl, 2-butenyl, 3-butenyl, isobutenyl, n-2,4-pentadienyl, 3-methyl-2-butenyl, n-2-octenyl, n-2-dodecenyl, iso-dodecenyl, oleyl, n-2-octadecenyl or n4octadecenyl. Preference is given to alkenyl having 3 to 18, especially 3 to 12, for example 3 to 6, especially 3 to 4 carbon atoms.
Alkoxy having up to 18 carbon atoms is a branched or unbranched radical such as, for example, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, isobutoxy, pentoxy, isopentoxy, hexoxy, heptoxy, octoxy, decyloxy, tetradecyloxy, hexadecyloxy or octadecyloxy. Preference is given to alkoxy having 1 to 12, especially 1 to 8, for example 1 to 6, carbon atoms.
Oxygen- or sulfur-interrupted C2-C18-alkoxy is, for example, CH3xe2x80x94Oxe2x80x94CH2xe2x80x94, CH3xe2x80x94Sxe2x80x94CH2xe2x80x94, CH3xe2x80x94Oxe2x80x94CH2CH2Oxe2x80x94, CH3xe2x80x94Sxe2x80x94CH2CH2Oxe2x80x94, CH3xe2x80x94Oxe2x80x94(CH2)2xe2x80x94Oxe2x80x94(CH2)2xe2x80x94Oxe2x80x94, CH3xe2x80x94(Oxe2x80x94CH2CH2xe2x80x94)2Oxe2x80x94CH2CH2Oxe2x80x94, CH3xe2x80x94(Oxe2x80x94CH2CH2xe2x80x94)3Oxe2x80x94CH2CH2Oxe2x80x94 or CH3xe2x80x94(Oxe2x80x94CH2CH2xe2x80x94)4Oxe2x80x94CH2CH2Oxe2x80x94.
C1-C18-alkylene is a branched or unbranched radical such as, for example, methylene, ethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene, dodecamethylene or octadecamethylene. Preference is given to C1-C12alkylene, especially C1-C8alkylene.
Alkylidene having 2 to 20 carbon atoms is, for example, ethylidene, propylidene, butylidene, pentylidene, 4-methylpentylidene, heptylidene, nonylidene, tridecylidene, nonadecylidene, 1-methylethylidene, 1-ethylpropylidene or 1-ethylpentylidene. C2-C8-alkylidene is preferred.
Phenylalkylidene having 7 to 20 carbon atoms is, for example, benzylidene, 2-phenylethylidene or 1-phenyl-2-heptylidene. C7-C9phenylalkylidene is preferred.
C5-C8cycloalkylene is a saturated hydrocarbon group having two free valencies and at least one ring unit and is, for example, cyclopentylene, cyclohexylene, cycloheptylene or cyclooctylene. Cyclohexylene is preferred.
Unsubstituted or C1-C4alkyl-substituted phenylene or naphthylene is, for example, 1,2-, 1,3- or 1,4-phenylene, or 1,2-, 1,3-, 1,4-, 1,6-, 1,7-, 2,6- or 2,7-naphthylene. 1,4-Phenylene preferred.
C4-C18-alkylene which is interrupted by oxygen, sulfur or 
is, for example, xe2x80x94CH2CH2xe2x80x94Oxe2x80x94CH2CH2xe2x80x94, xe2x80x94CH2CH2xe2x80x94Sxe2x80x94CH2CH2xe2x80x94, xe2x80x94CH2CH2xe2x80x94NHxe2x80x94CH2CH2xe2x80x94, xe2x80x94CH2CH2xe2x80x94N(CH3)xe2x80x94CH2CH2xe2x80x94, xe2x80x94CH2CH2xe2x80x94Oxe2x80x94CH2CH2xe2x80x94Oxe2x80x94CH2CH2xe2x80x94, xe2x80x94(CH2)2xe2x80x94(Oxe2x80x94CH2CH2xe2x80x94)2Oxe2x80x94(CH2)2xe2x80x94, xe2x80x94(CH2)2xe2x80x94(Oxe2x80x94CH2CH2xe2x80x94)3Oxe2x80x94(CH2)2xe2x80x94, xe2x80x94(CH2)2xe2x80x94(Oxe2x80x94CH2CH2xe2x80x94)4Oxe2x80x94(CH2)2xe2x80x94 or xe2x80x94CH2CH2xe2x80x94Sxe2x80x94CH2CH2xe2x80x94.
Particular mention is to be made of coating compositions comprising as component (b) at least one compound of the formula I or a salt derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II, in which R2 and R3 are hydrogen.
Advantageous coating compositions are those comprising as component (b) at least one compound of the formula I in which R1 is hydroxyl- or carboxyl-substituted C5-C12alkyl.
Preference is given to coating compositions comprising as component (b) at least one salt derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II in which
Rxe2x80x21 is C5-C18alkyl, or hydroxyl- or carboxyl-substituted C5-C12alkyl;
Rxe2x80x24 is hydrogen or hydroxyl, and
Rxe2x80x25 is C5-C25alkyl or 
Preference is also given to coating compositions comprising as component (b) at least one salt derived from i) a compound of formula Ixe2x80x2 and ii) an amine of the formula II in which
R14 and R15 independently of one another are hydrogen, C1-C8alkyl, or hydroxyl-substituted C2-C14alkyl; or R14 and R15, together with the nitrogen atom to which they are attached, form an oxygen-interrupted 6-membered heterocyclic ring,
X is a direct bond,
a is 1, and
R18 is C1-C14alkyl, hydroxyl-substituted C2-C14alkyl; unsubstituted or C1-C4alkyl-substituted phenyl; or is benzyl.
Also of interest are coating compositions comprising as component (b) at least one compound of the formula I or a salt derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II in which
R1 is hydroxyl-, carboxyl- or amino-substituted C5-C12alkyl; or R1 and R5, together with the nitrogen atom to which they are attached, form a 5-, 6- or 7-membered heterocyclic ring which is interrupted by oxygen, sulfur or 
Rxe2x80x21 is C5-C20alkyl, C5-C20alkyl which is interrupted by oxygen, sulfur or 
xe2x80x83hydroxyl-, carboxyl- or amino-substituted C5-C20alkyl; C5-C20alkenyl, C5-C8cycloalkyl, unsubstituted or C1-C4alkyl-substituted phenyl; benzyl or 
xe2x80x83or Rxe2x80x21 and Rxe2x80x25, together with the nitrogen atom to which they are attached, form a 6-membered heterocyclic ring which is unsubstituted or is substituted by C1-C4alkyl or is interrupted by oxygen, sulfur or 
R2 and R3 independently of one another are hydrogen, C1-C12alkyl, C5-C7cycloalkyl, phenyl or benzyl;
R4 is hydroxyl,
Rxe2x80x24 is hydrogen, hydroxyl or xe2x80x94OR8,
R5 is 
Rxe2x80x25 is hydrogen, C5-C20alkyl, C5-C20alkyl which is interrupted by oxygen, sulfur or 
xe2x80x83C5-C20alkenyl, C5-C8cycloalkyl, unsubstituted or C1-C4alkyl-substituted phenyl; benzyl or 
R6 is C1-C12alkyl or benzyl,
m is 0 or 1,
R7 is hydrogen or C1-C6alkyl,
R8 is C1-C6alkyl, cyclohexyl or phenyl,
R14 and R15 independently of one another are hydrogen, C1-C20alkyl, hydroxyl-substituted C2-C20alkyl, oxygen- or sulfur-interrupted C3-C20alkyl; C7-C9phenylalkyl; C3-C20alkenyl or 
xe2x80x83or R14 and R15, together with the nitrogen atom to which they are attached, form a 6-membered heterocyclic ring which is interrupted by oxygen, sulfur or 
R16 is C1-C20alkyl, oxygen- or sulfur-interrupted C2-C20alkyl; hydroxyl, C1-C12alkoxy or C2-C20alkenyl,
R17 is hydroxyl, C1-C12alkoxy, or oxygen- or sulfur-interrupted C2-C12alkoxy; and, if b is 0, three radicals R17 together are N(CH2CH2Oxe2x80x94)3,
X is a direct bond, C1-C12alkylene, C2-C12alkylidene, C7-C12phenylalkylidene, C5-C8cyclohexylene, phenylene, naphthylene, or oxygen- or sulfur-interrupted C4-C18alkylene, with the proviso that never two nitrogen atoms are attached to the same carbon atom,
a is 1 or 2,
b is 0, 1 or 2, and,
if a is 1,
R18 is hydrogen, C1-C20alkyl, hydroxyl-substituted C2-C20alkyl, oxygen- or sulfur-interrupted C3-C20alkyl; phenyl, C7-C9phenylalkyl, C3-C20alkenyl, 
if a is 2,
R18 is 
There is particular interest in coating compositions comprising as component (b) at least one compound of the formula I or a salt derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II in which
R1 is hydroxyl- or carboxyl-substituted C5-C11alkyl; or R1 and R5, together with the nitrogen atom to which they are attached, form an oxygen- or sulfur-interrupted 6-membered heterocyclic ring;
Rxe2x80x21 is C5-C20alkyl, oxygen- or sulfur-interrupted C5-C20alkyl; hydroxyl- or carboxyl-substituted C5-C11alkyl; C5-C10alkenyl, cyclohexyl, phenyl or benzyl, or Rxe2x80x21 and Rxe2x80x25, together with the nitrogen atom to which they are attached, form an oxygen- or sulfur-interrupted 6-membered heterocyclic ring;
R2 and R3 independently of one another are hydrogen, C1-C4alkyl, cyclohexyl, phenyl or benzyl,
R4 is hydroxyl,
Rxe2x80x24 is hydrogen or hydroxyl,
R5 is 
Rxe2x80x25 is C5-C20alkyl, oxygen- or sulfur-interrupted C5-C20alkyl; C5-C20alkenyl, cyclohexyl, phenyl, benzyl or 
m is 0,
R14 and R15 independently of one another are hydrogen, C1-C12alkyl, hydroxyl-substituted C2-C12alkyl, oxygen- or sulfur-interrupted C3-C12alkyl; benzyl, C3-C12alkenyl or 
xe2x80x83or R14 and R15, together with the nitrogen atom to which they are attached, form an oxygen- or sulfur-interrupted 6-membered heterocyclic ring;
R16 is C1-C12alkyl, oxygen- or sulfur-interrupted C2-C12alkyl; hydroxyl, C1-C12alkoxy or C2-C12alkenyl,
R17 is hydroxyl or C1-C12alkoxy; and, if b is 0, three radicals R17 together are N(CH2CH2Oxe2x80x94)3,
X is a direct bond, C1-C8alkylene, cyclohexylene, phenylene, naphthylene, or is oxygen-interrupted C4-C12alkylene, with the proviso that never two nitrogen atoms are attached to the same carbon atom,
a is 1 or 2,
b is 0, 1 or 2, and,
if a is 1,
R18 is hydrogen, C1-C12alkyl, hydroxyl-substituted C2-C12alkyl, oxygen-interrupted C3-C12alkyl; phenyl, benzyl, C3-C12alkenyl or 
if a is 2,
R18 is 
Coating compositions which are especially of particular interest are those comprising as component b) at least one compound of the formula I or a salt derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II in which
R1 is hydroxyl- or carboxyl-substituted C5-C11alkyl,
Rxe2x80x21 is C5-C18alkyl, or hydroxyl- or carboxyl-substituted C5-C11alkyl;
R2 is hydrogen,
R3 is hydrogen,
R4 is hydroxyl,
Rxe2x80x24 is hydrogen or hydroxyl,
R5 is 
Rxe2x80x25 is C5-C18alkyl or 
m is 0,
R14 and R15 independently of one another are hydrogen, C1-C4alkyl, or hydroxyl-substituted C2-C4alkyl; or R14 and R15, together with the nitrogen atom to which they are attached, form an oxygen-interrupted 6-membered heterocyclic ring,
X is a direct bond,
a is 1, and
R18 is C1-C4alkyl, hydroxyl-substituted C2-C4alkyl; or is phenyl.
Examples of particularly preferred amines of the formula II are n-butylamine, isobutylamine, tert-butylamine, n-iso-/tert-amylamine, n-hexylamine, n-heptylamine, n-octylamine, isooctylamine, tert-octylamine, n-nonylamine, n-decylamine, n-dodecylamine, isododecylamine, tert-dodecylamine, n-tridodecylamine, isotridecylamine, tert-tridodecylamine, n-tetradecylamine, isotetradecylamine, tert-tetradecylamine, n-octadecylamine, iso-octadecylamine, tert-octadecylamine, n-nonadecylamine, isononadecylamine, tert-nonadecylamine, n-eicosamine, iso-eicosamine, tert-eicosamine, n-heneicosamine, iso-heneicosamine, tert-heneicosamine, n-docosamine, iso-docosamine, tert-docosamine, n-tricosamine, isotricosamine, tert-tricosamin, n-tetracosamine, iso-tetracosamine, tert-tetracosamine, benzylamine, di-benzylamine, N-benzylaniline, di-n-butylamine, di-Isobutylamine, di-isodecylamine, di-tridodecylamine, di-isooctylamine, di-tert-octylamine, di-isotetradecylamine, di-n-octadecylamine, di-t-butylamine, di-n-octylamine, di-2-ethylhexylamine, di-n-dodecylamine, di-n-eicosylamine, di-n-tetraeicosylamine, 3-butoxypropylamine, hexoxybutylamine, nonyloxy-propylamine, aniline, N-methylaniline, N-ethylaniline, N,N-dimethylaniline, tri-n-butylamine, triisobutylamine, tri-noctylamine and in particular, ethanolamine, N,N-dimethylaminoethanol, tris(hydroxymethyl)-aminomethane (TRISAMINO), 2-amino-2-ethyl-1,3-propanediol (AEPD), 2-amino-2-methyl-1-propanol (AMP 95), 2-dimethylamino-2-methyl-1-propanol (DMAMP 80), 2-amino-2-methyl-1,3-propanediol, N-methylmorpholine, N-ethylmorpholine, triethanolamine, triethfylamine, ammonia, 3-aminopropyltrimethoxysilane, N-methyl-3-aminopropyl-trimethoxysilane, 3-aminopropylmethyidiethoxysilane, 3-aminopropylmethyidiethoxysilane, N-alkyl-3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, N,Nxe2x80x2-dimethyl-3-aminopropyl-triethoxysilane, N,Nxe2x80x2-dibutyl-3-aminopropyltrimethoxysilane, N,Nxe2x80x2-(di-2-hydroxyethyl)-3-aminopropyltrimethoxysilane, bis-[3-(triethylsilyl)propyl]amine, 3-(2-aminoethylamino)propyl-trimethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, 3-(6-aminohexylamino)propyltrimethoxysilane, 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane, aminophenyltrimethoxysilane and 3-aminopropyltrimethoxysilane. Particular preference is given to N-ethylmorpholine, N,N-dimethylaniline, triethanolamine, diethanolamine, triethylamine, ammonia, 3-aminopropyltrimethoxysilane and 3-aminopropyltrimethoxysilane.
Some of the compounds of the formula I and Ixe2x80x2 are known in the literature; others can be prepared in analogy to GB-A-2 121 419; K. Moedritzer et al., J. Org. Chem. 31, 1603-1607 (1966); Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], volume XII/1, pages 483-489 (1963); or volume E2, 302-304 (1982).
The compounds of the formula II, especially the amino silanes, are known from the literature or can be prepared in analogy to J. L. Speier et al., J.Org. Chem. 36 (21), 3120-3126 (1971); L. Birkofer et al., Chapter 10, pages 655 to 751 in S. Palai, Z. Pappoport xe2x80x9cThe Chemistry of Organic Silicon Compoundsxe2x80x9d, John Wiley and Sons Ltd., 1989; or E. P. Plueddeman, xe2x80x9cSilane Coupling Agentsxe2x80x9d, Plenum Press 1982, pages 1-233.
It is also possible to use mixtures of two or more different amines of the formula II for preparing the salts.
The salts derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II or iii) zirconium, bismuth or calcium are expediently prepared in situ in the course of the formulation of the coating composition. The present invention therefore relates to coating compositions comprising (axe2x80x2) an organic film-forming binder, (bxe2x80x2) at least one acid of the formula Ixe2x80x2, and (cxe2x80x2) at least one amine of the formula II or a zirconium, bismuth or calcium compound.
The present invention also relates to a process for preparing a coating composition comprising as component (b) at least one compound of the formula I or a salt derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II or iii) zirconium, bismuth or calcium, which comprises mixing an organic film-forming binder with the component (b).
The coating composition is preferably a coating material, especially an aqueous coating material.
Examples of coating materials are lacquers, paints or varnishes. These always contain an organic film-forming binder in addition to other, optional components.
Preferred organic film-forming binders are epoxy resins, polyurethane resins, amino resins, acrylic resins, acrylic copolymer resins, polyvinyl resins, phenolic resins, styrene/butadiene copolymer resins, vinyl/acrylic copolymer resins, polyester resins or alkyd resins, or a mixture of two or more of these resins, or an aqueous basic or acidic dispersion of these resins or mixtures of these resins, or an aqueous emulsion of these resins or mixtures of these resins.
Of particular interest are organic film-forming binders for aqueous coating compositions, such as, for example, alkyd resins; acrylic resins, two-component epoxy resins; polyurethane resins; polyester resins, which are usually saturated; water-dilutable phenolic resins or derived dispersions; water-dilutable urea resins; resins based on vinyl/acrylic copolymers; and hybrid systems based on, for example, epoxy acrylates.
More specifically, the alkyd resins can be water-dilutable alkyd resin systems which can be employed in air-drying form or in the form of stoving systems, optionally in combination with water-dilutable melamine resins; the systems may also be oxidatively drying, air-drying or stoving systems which are optionally employed in combination with aqueous dispersions based on acrylic resins or copolymers thereof, with vinyl acetates, etc.
The acrylic resins can be pure acrylic resins, epoxy acrylate hybrid systems, acrylic acid or acrylic ester copolymers, combinations with vinyl resins, or copolymers with vinyl monomers such as vinyl acetate, styrene or butadiene. These systems can be air-drying systems or stoving systems.
In combination with appropriate polyamine crosslinkers, water-dilutable epoxy resins exhibit excellent mechanical and chemical resistance. If liquid epoxy resins are used, the addition of organic solvents to aqueous systems can be omitted. The use of solid resins or solid-resin dispersions usually necessitates the addition of small amounts of solvent in order to improve film formation.
Preferred epoxy resins are those based on aromatic polyols, especially those based on bisphenols. The epoxy resins are employed in combination with crosslinkers. The latter may in particular be amino- or hydroxy-functional compounds, an acid, an acid anhydride or a Lewis acid. Examples thereof are polyamines, polyaminoamides, polysulfide-based polymers, polyphenols, boron fluorides and their complex compounds, polycarboxylic acids, 1,2-dicarboxylic anhydrides or pyromellitic dianhydride.
Polyurethane resins are derived from polyethers, polyesters and polybutadienes with terminal hydroxyl groups, on the one hand, and from aliphatic or aromatic polyisocyanates on the other hand.
Examples of suitable polyvinyl resins are polyvinylbutyral, polyvinyl acetate or copolymers thereof.
Suitable phenolic resins are synthetic resins in the course of whose construction phenols are the principal component, i.e. in particular phenol-, cresol-, xylenol- and resorcinol-formaldehyde resins, alkylphenolic resins, and condensation products of phenols with acetaldehyde, furfurol, acrolein or other aldehydes. Modified phenolic resins are also of interest.
The coating compositions may additionally comprise one or more components taken, for example, from the group consisting of pigments, dyes, fillers, flow control agents, dispersants, thixotropic agents, adhesion promoters, antioxidants, light stabilizers and curing catalysts. They may also include other known anticorrosion agents, for example anticorrosion pigments, such as phosphate- or borate-containing pigments or metal oxide pigments or other organic or inorganic corrosion inhibitors, for example salts of nitroisophthalic acid, phosphoric esters, technical-grade amines or substituted benzotriazoles.
The pigments are, for example, titanium dioxide, iron oxide, aluminum bronze or phthalocyanine blue.
Examples of fillers are talc, alumina, aluminum silicate, barytes, mica, and silica. The corrosion inhibitors can be applied to a support material. Pulverulent fillers or pigments are particularly suitable for this purpose.
Flow control agents and thixotropic agents are based, for example, on modified bentonites.
Adhesion promoters are based, for example, on modified silanes.
Also of advantage is the addition of basic fillers or pigments, which in particular binder systems give rise to a synergistic effect on corrosion inhibition. Examples of such basic fillers and pigments are calcium carbonate or magnesium carbonate, zinc oxide, zinc carbonate, zinc phosphate, magnesium oxide, alumina, aluminum phosphate or mixtures thereof. Examples of basic organic pigments are those based on aminoanthraquinone.
The corrosion inhibitors can be added to the coating material during its preparation, for example during pigment dispersion by grinding, or the inhibitor is dissolved in a solvent and the solution is then stirred into the coating composition. The solutions, especially aqueous solutions, of the corrosion inhibitors can also be used for pretreating the metal surface, which can then be subsequently coated with a topcoat.
In the preparation of the organic film-forming binder by addition polymerization or condensation polymerization of monomers, the corrosion inhibitors can be mixed in solid form, or dissolved, with the monomers even prior to the polymerization reaction.
The novel compounds of the formula I or salts derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II or iii) zirconium, bismuth or calcium are expediently used in an amount of from 0.01 to 20% by weight, preferably from 0.05 to 5% by weight, in particular from 0.1 to 5% by weight, based on the weight of the overall solids content of the coating composition.
The coating materials can be applied to the substrate by the customary techniques, for example by spraying, dipping, spreading or electrodeposition. In many cases, a plurality of coats are applied. The corrosion inhibitors are added primarily to the base layer (primer), since they are active in particular at the metavcoating interface. However, they can also be added to the intermediate coat or topcoat, as well. Depending on whether the binder is a physically, chemically or oxidatively drying resin or a heat-curing or radiation-curing resin, the coating is cured at room temperature or by heating (stoving) or by irradiation.
The coating material is preferably a primer for metallic substrates such as, for example, iron, steel, copper, zinc or aluminum, and alloys thereof.
In addition to the anticorrosive effect, the compounds of the formula I or the salts derived from i) a compound of formula Ixe2x80x2 and ii) an amine of the formula II or iii) zirconium, bismuth or calcium have the advantage that they favourably affect the adhesion between coating and metal, show no adverse effects on the storage stability of the novel coating compositions, and exhibit good compatibility with the binder.
A preferred embodiment of the present invention is therefore the use of the compounds of the formula I or salts derived from i) compounds of the formula Ixe2x80x2 and ii) amines of the formula II or iii) zirconium, bismuth or calcium as corrosion inhibitors in coating compositions for metallic surfaces.
The present invention also relates to a process for protecting a corrodable metal substrate, which comprises applying thereto a coating composition comprising as component (a) an organic film-forming binder and as component (b) at least one compound of the formula I or at least one salt derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II or iii) zirconium, bismuth or calcium, and then drying and/or curing the coating composition.
The present invention likewise relates to a process for preparing a corrosion-resistant surface coating on a corrodable metal surface, which comprises treating this surface with a coating composition comprising as component (a) an organic film-forming binder and as component (b) at least one compound of the formula I or at least one salt derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II or iii) zirconium, bismuth or calcium, and then drying and/or curing the coating composition.
The present invention relates, moreover, to a process for pretreating metal surfaces, which comprises applying to the metal surface an aqueous solution of a component (b) comprising at least one compound of the formula I or at least one salt derived from i) a compound of the formula Ixe2x80x2 and ii) an amine of the formula II or iii) zirconium, bismuth or calcium, and drying it.
The invention further relates to novel compounds of the formula I 
in which
R1 is hydroxyl- or amino-substituted C4-C12alkyl; or R1 and R5, together with the nitrogen atom to which they are attached, are a 5-, 6- or 7-membered heterocyclic ring which is unsubstituted or is substituted by C1-C4alkyl or is interrupted by oxygen, sulfur or 
R2 and R3 independently of one another are hydrogen, C1-C20alkyl, C5-C8cycloalkyl, unsubstituted or C1-C4alkyl-substituted phenyl; or benzyl,
R4 is hydroxyl,
R5 is 
R6 is C1-C18alkyl or C7-C9phenylalkyl, and
m is 0 or 1; and with the proviso that the compound of the formula III 
xe2x80x83is excluded.
Preferred groups of novel compounds of the formula I correspond to the preferences expressed above for the coating compositions.
Preference is given, moreover, to compounds of the formula I in which
R1 is hydroxyl-substituted C5-C11alkyl; or R1 and R5, together with the nitrogen atom to which they are attached, form an oxygen- or sulfur-interrupted 6-membered heterocyclic ring;
R2 and R3 independently of one another are hydrogen, C1-C4alkyl, cyclohexyl, phenyl or benzyl,
R4 is hydroxyl,
R5 is 
xe2x80x83and
m is 0.
Also of interest are compounds of the formula I in which
R1 is hydroxyl-substituted C5-C8alkyl,
R2 is hydrogen,
R3 is hydrogen,
R4 is hydroxyl,
R5 is 
xe2x80x83and
m is 0.
The invention additionally relates to novel salts derived from i) a compound of the formula Ixe2x80x3 
in which
Rxe2x80x31 is C8-C14alkyl, hydroxyl-, carboxyl- or amino-substituted C4-C14alkyl; C8-C14 alkenyl or 
xe2x80x83or Rxe2x80x31 and Rxe2x80x35, together with the nitrogen atom to which they are attached, form a 5-, 6- or 7-membered heterocyclic ring which is unsubstituted or substituted by C1-C4alkyl or is interrupted by oxygen, sulfur or 
R2 and R3 independently of one another are hydrogen, C1-C20alkyl, C5-C8cycloalkyl, unsubstituted or C1-C4alkyl-substituted phenyl; or are benzyl,
Rxe2x80x34 is hydrogen or hydroxyl,
Rxe2x80x35 is hydrogen, C8-C14alkyl, C2-C24alkenyl or 
R6 is C1-C18alkyl or C7-C9phenylalkyl, and m is 0 or 1; with the proviso that, if Rxe2x80x31 or Rxe2x80x35 is hydrogen, m is 0; and
ii) an amine of the formula II 
xe2x80x83in which
R14 and R15 independently of one another are hydrogen, C1-C25alkyl, hydroxyl-substituted C2-C24alkyl, oxygen- or sulfur-interrupted C3-C25alkyl; C7-C9phenylalkyl which is unsubstituted or is substituted on the phenyl ring by C1-C4alkyl; C3-C24alkenyl or 
or R14 and R15, together with the nitrogen atom to which they are attached, form a 5-, 6- or 7-membered heterocyclic ring which is unsubstituted or is substituted by C1-C4alkyl or is interrupted by oxygen, sulfur or 
R7 is hydrogen or C1-C6alkyl,
R16 is C1-C25alkyl, oxygen- or sulfur-interrupted C2-C25alkyl; hydroxyl, C1-C18alkoxy or C2-C24alkenyl,
R17 is hydroxyl, C1-C18alkoxy, or oxygen- or sulfur-interrupted C2-C18alkoxy; and, if b is 0, three radicals R17 together are N(CH2CH2Oxe2x80x94)3,
X is a direct bond, C1-C18alkylene, C2-C20alkylidene, C7-C20phenylalkylidene, C5-C8-cycloalkylene, unsubstituted or C1-C4alkyl-substituted phenylene or naphthylene; or
C4-C18alkylene which is interrupted by oxygen, sulfur or 
xe2x80x83with the proviso that never two nitrogen atoms are attached to the same carbon atom,
a is 1 or 2,
b is 0, 1 or 2, and,
if a is 1,
R18 is hydrogen, C1-C25alkyl, hydroxyl-substituted C2-C24alkyl, oxygen- or sulfur-interrupted C3-C25alkyl; unsubstituted or C1-C4alkyl-substituted phenyl; C7-C9phenylalkyl which is unsubstituted or is substituted on the phenyl ring by C1-C4alkyl; C3-C24alkenyl, 
xe2x80x83and,
if a is 2,
R18 is 
xe2x80x83and with the proviso that the compound of the formula II is not ammonia, triethanolamine or ethylamine; or
iii) zirconium, bismuth or calcium.
Preferred groups of novel salts correspond to the preferences expressed above for the coating compositions.
Preference is given, moreover, to salts derived from i) a compound of the formula Ixe2x80x3 and ii) an amine of the formula II or iii) zirconium, bismuth or calcium in which
Rxe2x80x31 is C8-C14alkyl, hydroxyl- or carboxyl-substituted C5-C14alkyl; or is C8-C12alkenyl, or Rxe2x80x31 and Rxe2x80x35, together with the nitrogen atom to which they are attached, form an oxygen- or sulfur-interrupted 6-membered heterocyclic ring;
R2 and R3 independently of one another are hydrogen, C1-C4alkyl, cyclohexyl, phenyl or benzyl,
Rxe2x80x34 is hydrogen or hydroxyl,
Rxe2x80x35 is C8-C14alkyl, C5-C20alkenyl or 
m is 0,
R14 and R15 independently of one another are hydrogen, C1-C12alkyl, hydroxyl-substituted C2-C12alkyl, oxygen- or sulfur-interrupted C3-C12alkyl; benzyl, C3-C12alkenyl or 
xe2x80x83or R14 and R15, together with the nitrogen atom to which they are attached, form an oxygen- or sulfur-interrupted 6-membered heterocyclic ring;
R16 is C1-C12alkyl, oxygen- or sulfur-interrupted C2-C12alkyl; hydroxyl, C1-C12alkoxy or C2-C12alkenyl,
R17 is hydroxyl or C1-C12alkoxy; and, if b is 0, three radicals R17 together are N(CH2CH2Oxe2x80x94)3,
X is a direct bond, C1-C8alkylene, cyclohexylene, phenylene, naphthylene, or oxygen-interrupted C4-C12alkylene, with the proviso that never two nitrogen atoms are attached to the same carbon atom,
a is 1 or 2,
b is 0, 1 or 2, and,
if a is 1,
R18 is hydrogen, C1-C12alkyl, hydroxyl-substituted C2-C12alkyl, oxygen-interrupted C3-C12alkyl; phenyl, benzyl, C3-C12alkenyl or 
xe2x80x83and
if a is 2,
R18 is 
Also of interest are salts derived from i) a compound of the formula Ixe2x80x3 and ii) an amine of the formula II or iii) zirconium, bismuth or calcium in which
Rxe2x80x31 is C8-C14alkyl, or hydroxyl- or carboxyl-substituted C5-C11alkyl;
R2 is hydrogen,
R3 is hydrogen,
Rxe2x80x34 is hydrogen or hydroxyl,
Rxe2x80x35 is C8-C14alkyl or 
m is 0,
R14 and R15 independently of one another are hydrogen, C1-C4alkyl, or hydroxyl-substituted C2-C4alkyl; or R14 and R15, together with the nitrogen atom to which they are attached, form an oxygen-interrupted 6-membered heterocyclic ring,
X is a direct bond,
a is 1, and
R18 is C14alkyl, or hydroxyl-substituted C2C4alkyl; or is phenyl.
The novel amine salts are of good solubility in water ( greater than 1 g/litre at 25xc2x0 C.), and the novel zirconium, bismuth and calcium salts are poorly water-soluble ( less than  less than 1 g/Litre at 25xc2x0 C.).
The salts are expediently prepared by reacting a compound of the formula Ixe2x80x2 or Ixe2x80x3 with an amine of the formula II or, respectively, with a zirconium, bismuth or calcium compound.
Preferably, equimolar amounts of the compounds of the formula Ixe2x80x2 or Ixe2x80x3 and amines of the formula II are mixed with one another in a temperature range from 10 to 80xc2x0 C., in particular from room temperature to 60xc2x0 C., as they are or in a dipolar aprotic solvent, for example dichloromethane, or in a protic solvent, for example ethanol, and are reacted. Where the compound of the formula Ixe2x80x2 or Ixe2x80x3 possesses two or more acid groups in the molecule, then one equivalent of the amine of the formula II is employed for each individual acid group.
Some of the compounds of the formula Ixe2x80x2 or Ixe2x80x3 are known in the literature; otherwise, they can be prepared in analogy to GB-A-2 121 419; K. Moedritzer et al., J. Org. Chem. 31, 1603-1607 (1966); Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], volume XII/1, pages 483-489 (1963); or volume E2, 302-304 (1982).
Some of the amine oxides of the compounds of the formula I, Ixe2x80x2 or Ixe2x80x3, in which m is 1, are known and can be prepared in a known manner, for example by oxidizing the corresponding tertiary amines with an appropriate oxidizing agent, such as a peroxide compound, for example hydrogen peroxide, sodium peroxide, percarbonates, perborates, persulfates, peracids. The oxidation procedure is normally carried out in an aqueous medium [see e.g. Hoh et al. xe2x80x9cHydrogen Peroxide Oxidation of Tertiary Aminesxe2x80x9d, The Journal of the American Oil Chemists"" Society, Vol. LV, No. 7, p. 268-271 (July 1963)].
The zirconium, bismuth and calcium salts of compounds of the formula Ixe2x80x2 or Ixe2x80x3 can be prepared in a manner known per se. Preferably, a compound of the formula Ixe2x80x2 or Ixe2x80x3 is reacted with a zirconium, bismuth or calcium compound. Also of particular interest is the reaction of an alkali metal salt, especially a sodium salt, of the compound of formula Ixe2x80x2 or Ixe2x80x3 with a zirconium, bismuth or calcium compound.
As zirconium, bismuth or calcium compound it is expedient to employ an organic zirconium, bismuth or calcium compound or an inorganic zirconium, bismuth or calcium compound.
Examples of organic zirconium, bismuth or calcium compounds are, in particular, alcoholates, for example zirconium n-propoxide, zirconium isopropoxide, zirconium n-butoxide, bismuth n-propoxide; bismutthisopropoxide; or carboxylates for example acetate""s especially zirconium acetate.
Examples of inorganic zirconium, bismuth or calcium compounds are halides, especially chlorides, nitrates, carbonates, hydroxides and sulfates. Zirconium carbonate, zirconium sulfate, zirconium oxide chloride, zirconium hydroxide, bismuth carbonate, bismuth sulfate, bismuth hydroxide and calcium carbonate are particularly advantageous.
The zirconium and bismuth salts of compounds of the formula Ixe2x80x2 or Ixe2x80x3 can also be referred to as zirconium and bismuth complexes.
In the preparation of zirconium, bismuth or calcium salts starting from compounds of the formula Ixe2x80x2 or Ixe2x80x3 and inorganic zirconium, bismuth or calcium compounds, such as, for example, zirconium carbonate, reaction is preferably carried out in water at elevated temperature, in particular at temperatures from 50 to 100xc2x0 C.
Reaction also takes place in a mixture of organic solvent with water. Particularly preferred mixtures are those of water with aromatic hydrocarbons, such as toluene or xylene, for example, or alcohols, for example methanol, ethanol, n-propanol, isopropanol, n-butanol or 2-butanol. Particular preference is given to toluene, ethanol and 2-butanol. The ratio of water to organic solvent can be varied as desired. Preference is given to a solvent ratio, for example, of water to toluene or water to alcohol (volume:volume) of from 1:10 to 10:1, in particular from 1:5 to 5:1, for example from 1:2 to 2:1.
When using organic zirconium or bismuth compounds such as, for example, zirconium n-propoxide, it is preferred to operate in an anhydrous organic solvent. Suitable organic solvents are all those which are chemically inert towards bases under the reaction conditions. Preference is given to aromatic hydrocarbons such as, for example, toluene or xylene; to aliphatic hydrocarbons such as, for example, pentane, hexane, heptane or octane and their isomer mixtures; to halogenated hydrocarbons such as, for example, di- or trifluoromethane or 1,2-dichloroethane; to ethers such as, for example, diethyl ether, dibutyl ether, 1,4-dioxane or tetrahydrofuran; and to acetonitrile, dimethylformamide, dimethyl sulfoxide or N-methylpyrrolidone.
In the preparation of zirconium or bismuth salts starting from compounds of the formula Ixe2x80x2 or Ixe2x80x3 and organic zirconium or bismuth compounds, the reaction is preferably carried out in toluene at elevated temperature, in particular at temperatures from 30 to 80xc2x0 C.
The hydrolysis of the zirconium and bismuth complexes of compounds of the formula Ixe2x80x2 or Ixe2x80x3, prepared from the organic zirconium and bismuth compounds and the compounds of the formula Ixe2x80x2 or Ixe2x80x3, is expediently carried out as a suspension in water. The products are preferably isolated by filtering the reaction mixture and then drying the residue at room temperature under a high vacuum.
The reaction of alkali metal salts of compounds of the formula Ixe2x80x2 or Ixe2x80x3, especially sodium salts, with inorganic zirconium, bismuth or calcium compounds, for example zirconium sulfate, to give the zirconium, bismuth or calcium salts of compounds of the formula Ixe2x80x2 or Ixe2x80x3 is preferably carried out in a solvent, for example water, or in a mixture of water and an organic solvent at room temperature. The products are preferably isolated by filtering the reaction mixture and then drying the residue at room temperature under a high vacuum.
The alkali metal salts of compounds of the formula Ixe2x80x2 or Ixe2x80x3 can also be prepared in situ from the corresponding compound of the formula Ixe2x80x2 or Ixe2x80x3 with one equivalent of dilute alkali metal hydroxide solution.
With respect to the zirconium or bismuth compound employed the compounds of the formula Ixe2x80x2 or Ixe2x80x3 can be used in excess, in equimolar amounts, or in deficit amounts. The molar ratio of the compound of the formula Ixe2x80x2 or Ixe2x80x2 to the zirconium or bismuth compound can be from 20:1 to 1:10. Preference is given to a ratio of from 10:1 to 1:3.
The present invention therefore also relates to a process for preparing the novel zirconium and bismuth salts, wherein the molar ratio of the compound of the formula Ixe2x80x2 or Ixe2x80x3 to the zirconium or bismuth compound is from 20:1 to 1:10.
The present invention additionally relates to a coating composition comprising a) an organic film-forming binder and b) as corrosion inhibitor at least one zirconium or bismuth complex, obtainable by reacting a compound of the formula Ixe2x80x2 or Ixe2x80x3 or an alkali metal salt thereof with a zirconium or bismuth compound, where the molar ratio of the compound of the formula Ixe2x80x3 or Ixe2x80x3 to the zirconium or bismuth compound is from 20:1 to 1:10, in particular from 10:1 to 1:5, for example from. 5:1 to 1:3.
The novel salts of compounds of the formula Ixe2x80x2 or Ixe2x80x3 can also be complexed with free acid (formula Ixe2x80x2 or Ixe2x80x3), with water or with other anions, such as hydroxides, which are present in the reaction medium. In the case of zirconium acetates or zirconium alkoxides, the acetate anions or the alkoxide anions may be present in the zirconium complexes of compounds of the formula Ixe2x80x2 or Ixe2x80x3.
On the basis of the comments made above, the percentage metal content by weight in the zirconium or bismuth complexes of the compounds of the formula Ixe2x80x2 or Ixe2x80x3 can be different. Preferred complexes have a metal content of from 5 to 50% by weight, preferably from 5 to 45% by weight, for example from 5 to 40% by weight.
The structures of the zirconium and bismuth salts of compounds of the formula Ixe2x80x2 or Ixe2x80x3 can be varied depending on the method of preparation and on the molar ratios of the compounds of the formula Ixe2x80x2 or Ixe2x80x3 and zirconium or bismuth compounds that are employed.
The present invention therefore also relates to products obtainable by reacting a compound of the formula Ixe2x80x2 or Ixe2x80x3 or an alkali metal salt thereof with a zirconium or bismuth compound.